Grease product



Patented Nov. 28, 1933 UNITED STATES 1,936,632 GREASE PRODUCT Erwin R. Lederer,

Fort Worth, Tex.

No Drawing. Application October 4, 1930 Serial No. 486,515

4 Claims.

This invention relates to improvements in grease products for lubricating purposes and particularly for lubricating the rockerarms and similar hearings in internal combustion engines used 5 for aviation purposes.

In the present day aviation engines the rockerarm for the valve control is particularly subject to unusual wear and requires careful lubrication which has heretofore been impossible, inasmuch as the ordinary oils will run off the rockerarm bearing and/or the invented cups and the rockerarm cannot normally be lubricated by a continuous fresh oil supply. The use of grease has not proved satisfactory as the present day greases are either objectionable because of inadequate or undesirable physical properties or because of hydrolysis and corrosion and have therefore not been used to any great extent.

The principal object of this invention is theregg fore the provision of a grease suitable for rockerarm and other lubrication, the base of which is an oil combined with aluminum soap and which has valuable lubricating .properties and which is substantially free from corrosive action and decomposition.

Another object of this invention is to provide a new and useful lubricating grease suitable for lubricating airplane engine rockerarms and other moving parts consisting of a, mixture of steamrefined mineral oil and aluminum soaps, the soap being formed by the mixture of aluminum hydroxide with both saturated and unsaturated fatty acids. Another object of this invention is to provide a lubricating grease having an aluminum hydroxide base soap which is less subject to hydrolysis and which is more stringy and sticky than heretofore known greases, and which by varying the proportion of the unsaturated acid soap to the saturated acid aluminum soap can be controlled as to stability, stringiness and stickiness.

Another object of this invention is to provide a grease having an aluminum soap base, made from saturated fatty acids and unsaturated fatty acids combined with a steam refined residual cylinder oil of high viscosity.

Another object of my invention is to provide an aluminum soap base lubricant made from a high viscosity steam refined oil and which is protested against premature hydrolysis and decomposition and which has satisfactory lubricating qualities at high temperatures and pressures.

Further objects and advantages of this inventionwill appear from the following description of a preferred formula of compounding the lubriv eating grease, it being understood that slight variances might occur in the formula without departing from the scope and spirit of my invention.

The lubrication of rockerarms and other parts of internal combustion engines and particularly of the aviation type has been especially difiicult andit has heretofore been proposed to use a grease having an aluminum soap base which is blended with acid treated low viscosity oils. Such a grease, however, even having an aluminum soap base is objectionable because the occasional moisture which mayreach the rockerarm bearing causes hydrolysis, particularly with the higher concentrations of soap and when the grease is made of acid treated oil. Furthermore, aluminum soap greases made of the saturated type of acid, such as stearic and palmitic acids, are of a gel-like nature, short in fiber and have other undesirable physical characteristics.

It has been my discovery that stability, stickiness and stringiness can be combined in one product which has more desirable physical properties if the aluminum soap used as the base is formed principally from saturated fatty acids and a smaller part but not less than 20% of an unsaturated fatty acid. It is thus possible to combine the more 'stable aluminum soaps with the better physical properties of the less stable unsaturated fatty acid and it is found that the re sulting grease provides a more desirable and longer life lubricant and is less subject to hydrolysis due to moisture.

Aluminum soaps are manufactured by combining in a suitable manner aluminum hydroxide with some fatty acid. The fatty acidused for this purpose can bedivided into two groups, namely: v

1. A saturated type in which the carbon chain contains no double bonds such as stearic, palmitic acids, etc. I

2. The unsaturated type in which the carbon chain contains one or more double bonds such as oleic, levulinic, rhinoleic acids, etc.

It is generally recognized that aluminum soap greases made from the first type of acids are of a gel-like nature, short in fiber, whilethose made from the second type are sticky and stringy. It has been my discovery that certain mixtures of the aluminum soap of these two types of acids with oil produces greases, the nature of which can be controlled by varying the amount of saturated and unsaturated fatty acid soaps in the mixture, and that such greases are particularly adapted for the lubrication of rockerarms in aviation engines and other moving parts where- 110 in a comparative stable solid grease is necessary. Such a mixture may consist for the larger part of aluminum soaps of the saturated fatty acids and for the smaller part but not less than 20% of the aluminum soaps of the unsaturated fatty acids. I' have also found that the use of approximately 10% of said aluminum soaps to 90% of steam refined paraffin base residual mineral oil produce a most desirable lubricating grease and that the use of acid treated oils or distillates are not as satisfactory as a residual oil because of their tendency to permit hydrolysis. It will be understood, however, that any suitable mineral lubricating oil may be used in place of the preferred steam refined oil.

I have found it desirable to use a steam-refined mineral oil of high viscosity in the nature of at least 150 Saybolt viscosity. at 210 F. and preferably made from a paraffin base crude. Approximately 10% of aluminum soap mixed as described above is mixed cold with 90% of steamrefined mineral oil, the oil and soap being stirred well together and the mixture heated with closed steam to 300 to 310 F. to drive off any moisture, and is then drawn off into flat pans and allowed to cool and set. Larger percentages of danger of hydrolysis in rainy weather which in- Y creases with the concentration of the soap and smaller portions than 10% form a grease which is too thin at the temperatures of'operation and will not remain in the cup for this reason.

It is preferable to use a residual oil of not less than 150 Sayboltviscosity at 210 F. made from a parafiin base crude and steam-refined in order to retain the protective colloids which, although their nature is unknown, are nevertheless pres ent in steam-refined residual oils and are not present in acid treated or distilled oils. These colloidal substances materially aid to reduce hydrolysis and prevent or at least retard breakdown of the aluminum soap.

The lubricant thus produced has the particular advantages of aluminum soap greases with sufficient consistency to be particularly adapted for aviation engine rockerarms, which require a continuous supply of lubricant under conditions of high temperature and pressure. The

lubricant resulting from the formula hereinbefore set forth does not run off the rockerarm bearings and/or the inverted cups as rapidly as available commercial forms of lubricant and on test has been found to last from two to ten times as long as similar lubricants made with the aluminum soaps now on the market, and there is less wear after alonger period of use due to the improved qualities and slower decomposition of this form of grease.

While I have described a preferred form of lubricant, I am aware that modifications may be made therein within the scope and spirit of my invention and I, therefore, desire a broad interpretation thereof within the scope and spirit of the disclosure heretofore set forth and of the claims appended hereinafter.

I claim:

1. A composition of matter for lubricants comprising a high viscosity steam-refined paraffin base residual mineral oil approximately 150 Saybolt viscosity at 210 F. and approximately 10% aluminum oleate and aluminum stearate which is I solid at 212 F.

2. A composition of matter for lubricants suitable for lubricating rockerarms of airplane engines and the like, comprising steam-refined viscous thread and being substantially solid at 4. A rocker arm lubricating grease comprising a steam refined heavy lubricating oil having colloidally dispersed therein about 10% of a mixture of aluminum soaps of saturated and unsaturated fatty acids, the soap of the unsaturated acids being in less proportion but not less than 20% of the soap mixture.

ERWIN R. LEDERER. 

